This Was a Woman 1948

The woman here is Sylvia Russell: power mad with set goals. In order to achieve those goals she is sadistically devoted to her son and daughter, able to possess and direct them. She subtly ruins her daughter's marriage by corrupting a servant girl and, then, uses her to compromise her son-in-law; slowly breaks her bumbling, unambitious husband's confidence...

Cast:

Sonia Dresdel
Sylvia Russell 

Walter Fitzgerald
Arthur Russell 

Emrys Jones
Terry Russell 

Barbara White
Fenella Russell 

Scott Forbes
Dr. Valentine Christie (billed as "Julian Dallas") 

Cyril Raymond
Austin Penrose